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SCIENCE

Water plays a key role in the evolution of terrestrial planets, and notably in the occurrence of Earth's oceans. However, the mechanism by which water has been incorporated into these bodies—including Earth—is still extensively debated. Here we report the detection of widespread 2.8 μm OH absorption bands on the surface of the asteroid Vesta by the VIR imaging spectrometer on board Dawn.

Before last July, Vesta was only a series of modest images brought to us by the Hubble Space telescope, enough to tantalize and inspire the Dawn mission, but essentially an unexplored new world in our solar system.